324 Horse Pox. 



the proven fact that occasionally diseases of persons producing the 

 lymph (syphilis, tuberculosis) are transmitted by the vaccination to 

 the persons being vaccinated. 



On account of this danger, l)ovine lymph is used exclusively in 

 recent times for vaccination. The vaccinating lymph is cultivated arti- 

 ficially in state or private establishments erected for the purpose. The 

 lymph is constantly re-inoculated from calf to calf, and then preserved 

 ])y a special method. For the original vaccine either original cow pox 

 lymph, or lymph of a calf vaccinated with humanized vaccine is used. 

 By employing calf lymph the danger of transmitting other diseases 

 may be excluded with certainty, by using young calves exclusively for 

 cultivation, and by placing the collected lymph on the market only after 

 the health of the vaccinated animals has been proven by an autopsy. 



At the present time the great practical value of pox vaccination 

 is recognized to such an extent that in most countries compulsory vac- 

 cination is established hy law, in spite of the fact that here and there 

 opposition is made against it. 



For the cultivation of the vaccine, weaned, healthy calves, preferably male 

 animals, are commonly used. These should previously be tested by tuberculin for 

 the presence of tuberculosis. The animal is secured lying on the side upon a 

 suitaljle table, the abdomen from the navel to the pubic-symphysis, or one-half 

 of the thorax, is shaved and thoroughly cleaned. Then the lymph from a ripe 

 vesicle of another calf, or of a vaccinated person, is inoculated into the skin of 

 the calf. The procedure is carried out by puncturing the skin in 100-200 points 

 into the deeper epithelial layers, or in such a manner that upon the surface of the 

 skin superficial incisions 1-2 cm. long are made, and the lymph is then rubbed into 

 the wounds. In from 4 to 5 days bluish nodules and vesicles on a bright reddened 

 bas-e develop at the point of vaccination, from which the lymph is pressed out 

 with suitable clamp forceps, and preserved either as pure lymph, or together with 

 epithelium, that is scraped off, mixed with equal parts of glycerin. 



The lymph is preserved in glass tubes, or painted in thin layers on ivory 

 plates 5 cm. long and 7 nmi. wide, the scraped fluid is enclosed between two small 

 glass plates and sealed with jjaraflfin. As in the lymph prepared in this manner 

 bacteria are destroyed within a few weeks without affecting the potency of the 

 lymph, only vaccine which is from 2 to 3 months ol<l is used for human vaccination. 



Literature. S. Huguenin, Ergebn. d. allg. Path., 1897, IV, 246. 



(c) Horse Pox. Variola equina. 



{Sore heels; Pferdepochen [German]; Variole equine [Freneli]; 

 Vajuolo equino [Italian].) 



Occurrence. Horse pox which was extensively studied by 

 Jenner, supposedly existed more frequently 3 or 4 decades ago, 

 and at that time periodically attained an epizootic extension 

 among horses. The descriptions liow^ever do not reveal a suf- 

 ficiently clear conception regarding the true nature of the affec- 

 tion observed, as English and French authors (among them 

 Bouley and Lafosse, also Nocard & Leclainche) understood 

 under the name of ''horse pox" that disease which since tlie 

 studies of Eggeling and Ellenberger (1878) is otherwise known 

 as contagious pustular stomatitis, and considered as an inde- 

 pendent affection (see p. 360). Jenner's horse pox is at 

 the present time so rare that some authors, among them Dieck- 

 erhoff, doubt its occurrence entirely. 



